The exact nature of the two men’s conversation, which took place after Gore met with Ivanka Trump (also on climate issues), has not been disclosed. But Gore, who has been urging world leaders to take man-made global warming seriously for more than a decade, called the meeting “extremely interesting,” and “very productive,” according to CNN. “It was a sincere search for areas of common ground,” Gore added.

It’s the latest indication that Trump may be softening his stance on global warming. In his first presidential debate against Hillary Clinton, Trump denied ever denying climate change. “I think it’s real,” he asserted during the debate. In a meeting with editors of the New York Times several weeks back, Trump elaborated on his newfound capacity for evidence-based reasoning, saying that he thinks “there is some connectivity” between humans and climate change.

“My hopeful side tells me that he does listen. But my concerned side is: who’s he going to listen to?”

Before we get too excited, however, it’s worth remembering that this is the same Trump who hired vocal climate denier Myron Ebell to head up the EPA’s transition team. Ebell, in addition to running a group “focused on dispelling the myths of global warming” has been known to refer to folks like Gore as “forces of darkness” who “want to turn off the lights all over the world.”

It is encouraging to hear that Trump’s views on climate change are not set in stone. But when the stakes are literally the future habitability of our planet, it’s also hard not to be extremely concerned.

“My hopeful side tells me that he does listen,” former NASA glaciologist Robert Bindschadler told me in a recent phone conversation. “But my concerned side is: who’s he going to listen to?”